1. Field of the Invention
The present invention relates to a sheet carrying device in which a skew of a sheet carried along a passage is corrected relative to a carrying direction.
2. Description of the Related Art
It is known that there is a photographic printer in which an image taken in a negative film is recorded on a photosensitive material. In this kind of the photographic printer, a strip of the photosensitive material is cut into a predetermined length in accordance with a print size, and the photosensitive material being as a sheet is exposed to record the image. However, if an anterior end of the photosensitive material skews at a time when the photosensitive material is exposed to record the image, the photosensitive material is exposed in a state that the image inclines. Consequently, the image is recorded in a slant state. Thus, in order to obtain a proper photographic print, it is required to correct the skew of the photosensitive material and to feed the photosensitive material to an exposing unit in a correct state having no skew.
It is known that there is a sheet carrying device in which a carrying roller pair for nipping and carrying the photosensitive material is inclined from a reference position, which is parallel to a width direction of a passage, in a direction perpendicular to the passage for the purpose of solving the above problem (see Japanese Patent Laid-Open Publication No. 2003-292198, for example). By inclining the carrying roller pair, both ends of the passage in the width direction have different lengths to correct the skew of the photosensitive material.
In the sheet carrying device described in the above-noted Publication No. 2003-292198, a skew corrector 50 makes the lengths of both ends of the passage difference. FIGS. 18A to 18C are development views of the passage having the different lengths at both ends thereof. As shown in these drawings, the passage lengths are different at both ends 17a and 17b of the passage 17. In a case the passage length of the right end 17b is longer than that of the left end 17a, the center CL2 of the photosensitive material inclines relative to the center CL1 of the passage in a counterclockwise direction while the photosensitive material 24a is carried along the passage 17 from a position shown in FIG. 18A to a position shown in FIG. 18B.
However, force applied by carrying roller pairs 35 and 36 continues to act for a posterior end of the photosensitive material 24a. When the photosensitive material 24a has a long length in the carrying direction, the force applied by the carrying roller pairs 35 and 36 acts in a long time. Thus, the posterior end of the photosensitive material 24a is reversely pushed, and the center CL2 of the photosensitive material 24a inclines relative to the center CL1 of the passage in a reverse direction (clockwise direction), such as shown in FIG. 18C. Hence, there arises a problem in that it is impossible to correct the skew, since a skew-correction amount of the photosensitive material 24a corrected by the skew corrector 50 is reduced.